High Efficiency Speaker Asylum

Posted by freddyi on October 12, 2000 at 21:59:24:

Hi -

I've built one double chamber reflex and used to have Bob Bullock's modeling program - to keep the port 'q' usable there is usally narrow-band response notch somewhere around the smaller chamber's resonance.

Also - it seemed George Augspurger's 2:1 chamber ratio was about as good as it got. The quick way to try the 'standard' dual chamber reflex is to pick a box volume and tuning from a standard 'alignment', divide the box into two volumes with one partitiion so one will be 33.3% of Vb and the other 66.6% then use two external vents which would tune the total volume to the desired Fb and then the third internal vent which couples the two chambers to each other is made the same size as the other vents.

I think they sound fine - the one I built with a 8" Vifa seemd less problematic than my transmission lines and diffusor-port reflex enclosures.

Also - I remember many years ago the drawing in Briggs book of an 'acoustic' filter whcih seemed to create a double chamber single external vent reflex by using a partition having 1/8" slots - may I ask what this really does? - It seems that the slots would give a fair amount of resitance to air flow - Briggs also showed these in his musical instument boxes - why did he do this and is there a use today for the 'acoustic' filter 2-chamber 1-external vent reflex?

Has anyone her messed with these reflex variants and if so what were your conclusions?

Thanks

Freddy

ps - sorry I'm not as 'hip' as the pros!